Anattack submarine orhunter-killer submarine is asubmarine specifically designed for the purpose of attacking and sinking other submarines,surface combatants, andmerchant vessels. In theSoviet andRussian navies they were and are called "multi-purpose submarines".[1] They are also used to protect friendly surface combatants andmissile submarines.[2] Some attack subs are also armed withcruise missiles, increasing the scope of their potential missions to include land targets.
Attack submarines may be eithernuclear-powered or diesel–electric ("conventionally") powered. In the U.S. Navynaming system, and in the equivalent NATO system (STANAG 1166), nuclear-powered attack submarines are known asSSNs and theiranti-submarine (ASW) diesel–electric predecessors areSSKs. In the U.S. Navy, SSNs are unofficially called "fast attacks".[3]
DuringWorld War II, submarines that fulfilled the offensive surface attack role were termedfleet submarines in the U.S. Navy and "ocean-going", "long-patrol", "type 1" or "1st class" by continental European navies.[4][5]
In theaction of 9 February 1945,HMS Venturer sankU-864 while both were atperiscope depth. This was the first and so far only intentional sinking of a submerged submarine by another submerged submarine.U-864 was snorkeling, thus producing much noise forVenturer'shydrophones (an early form of passivesonar) to detect, andVenturer was fortunate in having over 45 minutes to plot theU-boat's zig-zag course by observing the snorkel mast.Venturer's commander,James S. "Jimmy" Launders, was astute in assuming the U-boat would execute an "emergency deep" maneuver once it heard the torpedoes in the water, thus the "spread" of four torpedoes immediately available was aimed on that assumption. One hit, sinking the U-boat.[6][7]
Following World War II, advanced German submarines, especially theType XXI U-boat, became available to the Allies, particularly the U.S. Navy and the Soviet Navy. Initially, theType XVII U-boat, with a Walterhydrogen peroxide-fueledgas turbine allowing high sustained underwater speed, was thought to be more developed than was actually the case, and was viewed as the submarine technology of the immediate future. However, the Type XXI, streamlined and with a high battery capacity for high submerged speed, was fully developed and became the basis for most non-nuclear submarine designs worldwide through the 1950s.[8] In the U.S. Navy, theGreater Underwater Propulsion Power Program (GUPPY) was developed to modernize World War II submarines along the lines of the Type XXI.[9] By 1955 the U.S. Navy was using the term 'attack submarine' to describe the GUPPY conversions and the first postwar submarines (theTang class and theDarter).[10]
It was realized that theSoviet Union had acquired Type XXI and other advanced U-boats and would soon be putting their own equivalents into production. In 1948 the U.S. Navy prepared estimates of the number ofanti-submarine warfare (ASW)-capable submarines that would be needed to counter the hundreds of advanced Soviet submarines that were expected to be in service by 1960. Two scenarios were considered: a reasonable scenario assuming the Soviets would build to their existing force level of about 360 submarines, and a "nightmare" scenario projecting that the Soviets could build submarines as fast as the Germans had built U-boats, with a force level of 2,000 submarines. The projected U.S.SSK force levels for these scenarios were 250 for the former and 970 for the latter. Additional anti-surface (i.e., 'attack'),guided missile, andradar picket submarines would also be needed. By comparison, the total U.S. submarine force at the end of World War II, excluding obsolescent training submarines, was just over 200 boats.[8]
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A small submarine suitable for mass production was designed to meet the SSK requirement. This resulted in the three submarines of theK-1 class (later named theBarracuda class), which entered service in 1951. At 750long tons (760 t) surfaced, they were considerably smaller than the 1,650long tons (1,680 t) boats produced in World War II. They were equipped with an advanced passive sonar, the bow-mounted BQR-4, but had only fourtorpedo tubes. Initially, a sonar located around the conning tower was considered, but tests showed that bow-mounted sonar was much less affected by the submarine's own noise.
While developing the purpose-built SSKs, consideration was given to converting World War II submarines into SSKs. The less-capableGato class was chosen for this, as some of the deeper-divingBalao- andTench-class boats were being upgraded as GUPPYs.SevenGato-class boats were converted to SSKs in 1951–53. These had the bow-mounted BQR-4 sonar of the other SSKs, with four of the six bow torpedo tubes removed to make room for the sonar and its electronics. The four stern torpedo tubes were retained. Two diesel engines were removed, and the auxiliary machinery was relocated in their place and sound-isolated to reduce the submarine's own noise.[8][11]
The Soviets took longer than anticipated to start producing new submarines in quantity. By 1952 only ten had entered service.[12] However, production was soon ramped up. By the end of 1960 a total of 320 new Soviet submarines had been built (very close to the USN's 1948 low-end assumption), 215 of them were theProject 613 class (NATO Whiskey class), a smaller derivative of the Type XXI. Significantly, eight of the new submarines were nuclear-powered.[13][14]
USS Nautilus, the world's firstnuclear submarine, was operational in 1955; the Soviets followed this only three years later with their firstProject 627 "Kit"-class SSN (NATO November class). Since a nuclear submarine could maintain a high speed at a deep depth indefinitely, conventional SSKs would be useless against them:
By the fall of 1957,Nautilus had been exposed to 5,000 dummy attacks in U.S. exercises. A conservative estimate would have had a conventional submarine killed 300 times:Nautilus was ruled as killed only 3 times...Using their active sonars, nuclear submarines could hold contact on diesel craft without risking counterattack...In effect,Nautilus wiped out the ASW progress of the past decade.[15]
As the development and deployment of nuclear submarines proceeded, in 1957–59 the U.S. Navy's SSKs were decommissioned or redesignated and reassigned to other duties. It had become apparent that all nuclear submarines would have to perform ASW missions.
Research proceeded rapidly to maximize the potential of the nuclear submarine for the ASW and other missions. The U.S. Navy developed a fully streamlined hull form and tested other technologies with the conventionalUSS Albacore, commissioned in 1953. The new hull form was first operationalized with the three conventionalBarbel-class boats and the six nuclearSkipjack-class boats, when both classes entered service beginning in 1959. Both classes used the BQS-4 and BQR-2 bow mounted sonars.[16][17] TheSkipjack was declared the "world's fastest submarine" following trials, although the actual speed was kept secret.
Sonar research showed that a sonar sphere capable of three-dimensional operation, mounted at the very bow of a streamlined submarine, would increase detection performance. This was recommended byProject Nobska, a 1956 study ordered byChief of Naval Operations AdmiralArleigh Burke.[18] The one-offTullibee in 1960 and theThresher class starting in 1961 were the first with a bow-mounted sonar sphere, the BQQ-2; midships torpedo tubes angled outboard were fitted to make room for the sphere.[8][19]
Tullibee was a type of nuclear-powered SSK; technologically very successful, intentionally slow but ultra-quiet withturbo–electric drive. Her unexpectedly high cost compared with theThresher proved it was impossible to build a low-cost nuclear SSK (severalnuclear reactor features could not be scaled down beyond a certain point, includingradiation shielding). This result coupled with her lower performance was judged to be notcost-effective and the type was not repeated; the Navy decided to merge the hunter-killer role with the attack submarines, making the terms interchangeable.[20]Thresher was faster and had an increased diving depth, carried twice as many torpedoes, included comparable sound silencing improvements, and was commissioned only nine months later.[21]
Thresher's loss in April 1963 triggered a major redesign of subsequent U.S. submarines known as theSUBSAFE program.[17] However,Thresher's general arrangement and concept were continued in all subsequent U.S. Navy attack submarines.
Britain commissioned its first nuclear attack submarineHMS Dreadnought in 1963 with a U.S.S5W reactor. At the same time as theDreadnought construction, attempts were made to transfer U.S. reactor technology to Canada and the Netherlands. AdmiralHyman G. Rickover considered such technology to be obvious, but a visit to the Soviet nuclear icebreakerLenin reportedly "appalled him" and convinced him that he should cancel the transfers to retain secrets.[22][23]
The first fully streamlined Soviet attack submarines were theProject 671 "Yorsh" class (NATO Victor I class), which first entered service in 1967.[13][24]
China commissioned its first nuclear attack submarineChangzheng 1 (NATO Han class) in 1974, and France its firstRubis-class submarine in 1983.[25][26]
The only time in history that a nuclear attack submarine engaged and sank an enemy warship was in theFalklands War, when on 2 May 1982 theBritish nuclear submarineHMS Conqueror torpedoed and sank theArgentine light cruiserARA General Belgrano.[27]
The U.S. Navy commissioned the firstSeawolf andVirginia-class nuclear powered submarines in 1997 and 2004 respectively.
As of 2025 Brazil has a nuclear attack submarineunder construction,[28] India hasfinalized a nuclear attack submarine interim design,[29][30] and Australia has started a nuclear attack submarine program under theAUKUS security pact with UK and US assistance.[31]
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Conventional attack submarines have however remained relevant throughout the nuclear era, with the BritishOberon class and the SovietRomeo,Foxtrot,Tango andKilo classes being good examples which served during theCold War.
With the advent ofair-independent propulsion technology, these submarines have grown more and more capable. Examples include theType 212,Scorpène andGotland classes of submarine. The U.S. NavyleasedHSwMS Gotland to perform the opposing force role duringASW exercises tactics.[32] TheGotland caused a stir in 2005 when during training it "sank" the American carrierUSS Ronald Reagan.[33][34]
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Algerian National Navy operates sixKilo-class submarines.
Argentine Navy operates oneType 209 submarine as a pier-side trainer; oneTR-1700-class submarine remains in inventory but is inactive.
Royal Australian Navy operates sixCollins-class submarines.
Bangladesh Navy operates twoMing-class submarines.
Brazilian Navy operates fiveType 209 submarines and threeRiachuelo-class submarines.
Royal Canadian Navy operates fourVictoria-class submarines.
Chilean Navy operates twoType 209 submarines and twoScorpène-class submarines.
People's Liberation Army Navy operates sixShang-class submarines, threeHan-class submarines, seventeenYuan-class submarines, thirteenSong-class submarines, twelveKilo-class submarines, and fourMing-class submarines.
Republic of China Navy operates twoZwaardvis-class submarines, oneTench-class submarine and oneBalao-class submarine.
Colombian National Navy operates twoType 209 submarines and twoType 206 submarines.
Ecuadorian Navy operates twoType 209 submarines.
Egyptian Navy operates fourType 209 submarines and fourRomeo-class submarines.
French Navy operates twoRubis-class submarines and threeBarracuda-class submarines.
German Navy operates sixType 212 submarines.
Hellenic Navy operates sixType 209 submarines and fourType 214 submarines.
Indian Navy operates fourType 209 submarines, sixScorpène-class submarines, and sevenSindhughosh-class submarines.
Indonesian Navy operates threeNagapasa-class submarines and oneCakra-class submarine.
Islamic Republic of Iran Navy operates threeKilo-class submarines.
Israeli Navy operates fiveDolphin-class submarines, with a sixth on sea trials as of late 2024.
Italian Navy operates fourSauro-class submarines and fourType 212 submarines.
Japan Maritime Self-Defense Force operates nineOyashio-class submarines, twelveSōryū-class submarines, and threeTaigei-class submarines.[35]
Korean People's Navy operates twentyRomeo-class submarines.[citation needed]
Republic of Korea Navy operates nineJang Bogo-class submarines, nineType 214 submarines, and twoKSS-III submarines.
Royal Malaysian Navy operates twoScorpène-class submarines.
Myanmar Navy operates a singleKilo-class submarine, gifted by India,[36] and a singleMing-class submarine, purchased from China.
Royal Netherlands Navy operates threeWalrus-class submarines.
Royal Norwegian Navy operates sixUla-class submarines.
Pakistan Navy operates fiveAgosta-class submarines.
Peruvian Navy operates sixType 209 submarines.
Polish Navy operates oneKilo-class submarine.
Portuguese Navy operates twoType 214 submarines.
Romanian Naval Forces possesses a singleKilo-class submarine, though it is not operational.
Russian Navy operates tenAkula-class submarines, twoVictor III-class submarines, twoSierra-class submarines, and c. twenty-oneKilo-class submarines (of which nine are the "Improved Kilo" variant).
Republic of Singapore Navy operates twoSjöormen-class submarines and twoVästergötland-class submarines, all purchased from Sweden.
South African Navy operates threeType 209 submarines.
Spanish Navy operates oneAgosta-class submarine and oneS-80 Plus-class submarine as of late 2024.
Swedish Navy operates threeGotland-class submarines and oneSödermanland-class submarine.
Turkish Navy operates twelveType 209 submarines.
Royal Navy operates fiveAstute-class submarines as of late 2024.
United States Navy operates twenty-threeLos Angeles-class submarines, threeSeawolf-class submarines, and twenty-fourVirginia-class submarines.
Bolivarian Navy of Venezuela operates twoType 209 submarines.
Vietnam People's Navy operates sixKilo-class submarines.
Albanian Naval Force retired all four of itsWhiskey-class submarines in 1989.
Bulgarian Navy decommissioned its lastRomeo-class submarine,Slava in 2011.
Cuban Revolutionary Navy retired all three of itsFoxtrot-class submarines in the 1990s.
Royal Danish Navy retired its last twoKobben-class submarines and its loneNäcken-class submarine in 2005.
Libyan Navy retired its sixFoxtrot-class submarines from active service in 1984.
Montenegrin Navy decommissioned its lastHeroj-class submarine in 2006.
Navy of Serbia and Montenegro transferred its entire navy toMontenegro upon their independence in 2006.
Syrian Navy retired all three of itsWhiskey-class submarines in 1993.
Ukrainian Navy only submarine,Zaporizhzhia, was captured by the Russian Navy during the2014 Annexation of Crimea.
Austro-Hungarian Navy lost its entire fleet following the Empire's collapse after World War I.
Estonian Navy twoKalev-class submarines were seized by the Soviet Union in 1940. After Estonia regained independence in 1991, it took backEML Lembit, and was kept in ceremonial commission as the flagship until 2011.
Finnish Navy forced to decommission all five of its submarines following World War II under theParis Peace Treaty.
Latvian Naval Forces twoRonis-class submarines were seized by the Soviet Union in 1940.
Royal Thai Navy decommissioned its lastMatchanu-class submarine in 1951.
This article contains quotations from this source, which is available under aCreative Commons Attribution 4.0 International Licence.
This article incorporates text from thepublic domainDictionary of American Naval Fighting Ships.
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